Apparatus and methods of optimizing atrioventricular pacing delay intervals

Abstract

Provided herewith are methods and apparatus for optimizing an atrioventricular (AV) pacing delay interval. One manner described involves programming an AV interval in such a way that the time interval between the end of the P-wave (PWend) and the beginning of the QRS complex (QRSbeg) or ventricular pace stimulus (Vp) is close to or no less than a certain fixed value (e.g. 40 ms). This is defined as an optimized AV interval (AVopt) herein. The foregoing can be dynamically and chronically implemented in an implantable medical device such as a dual- or triple-chamber pacemaker. The PWend value is detected using a novel technique and sensing QRSbeg and/or Vp is achieved with traditional circuitry and components. Then automatic adjustment of an operating AV interval occurs until AVopt is identified. Thereafter, periodic, continuous, or manually-triggered performance of the foregoing can be implemented.

1 . An apparatus for adjusting an operating atrio-ventricular (AV) interval in a cardiac pacing therapy delivery device, comprising:
 a) means for programming an operating AV interval intended to produce a predetermined fixed period of time between an end of a P-wave (PWend) and the beginning of one of a corresponding paced QRS complex (QRSbeg) and delivery of a ventricular pacing stimulus (Vp);   b) means for monitoring an atrial depolarization;   c) means for locating the PWend associated with the atrial depolarization;   c) means for measuring an elapsed amount of time from the PWend to one of the QRSbeg and the Vp;   d) means for comparing the predetermined fixed period of time and the measured elapsed amount of time;   e) means for storing the operating AV interval as an optimized AV (AVopt) interval in a memory of the CRT delivery device if the values of the predetermined fixed period of time and the measured elapsed amount of time are within a prescribed tolerance range;   f) means for modifying the operating AV interval if the values of predetermined fixed period of time and the measured elapsed amount of time are not within the prescribed tolerance range; and   g) means for repeating the steps a) through f) until the AVopt interval is stored.   
   
   
       2 . An apparatus according to  claim 1 , further comprising:
 means for operating the CRT delivery device in a bi-ventricular pacing mode at the AVopt interval.   
   
   
       3 . An apparatus according to  claim 1 , wherein the means for setting the operating AV interval includes a means for programming a value of between about 100 ms and about 200 ms and wherein the predetermined fixed period of time is in the range of about 20 ms to about 60 ms. 
   
   
       4 . An apparatus for adjusting an operating atrio-ventricular (AV) interval in a cardiac pacing therapy delivery device, comprising:
 a) a computer processor disposed in a CRT delivery device programmed with an operating AV interval intended to produce a predetermined fixed period of time between an end of a P-wave (PWend) and the beginning of one of a corresponding paced QRS complex (QRSbeg) and delivery of a ventricular pacing stimulus (Vp);   b) a pair of sensing electrodes adapted to monitor an atrial depolarization;   c) means coupled to the computer processor for locating the PWend associated with the atrial depolarization;   c) means for measuring an elapsed amount of time from the PWend to one of the QRSbeg and the Vp;   d) means for comparing the predetermined fixed period of time and the measured elapsed amount of time;   e) means for storing the operating AV interval as an optimized AV (AVopt) interval in a memory of the CRT delivery device if the values of the predetermined fixed period of time and the measured elapsed amount of time are within a prescribed tolerance range;   f) means for modifying the operating AV interval if the values of predetermined fixed period of time and the measured elapsed amount of time are not within the prescribed tolerance range; and   g) means for repeating the steps a) through f) until the AVopt interval is stored.   
   
   
       5 . An apparatus according to  claim 4 , wherein the pacing delivery device operates in a bi-ventricular pacing mode at the AVopt interval. 
   
   
       6 . An apparatus according to  claim 4 , wherein the means for setting the operating AV interval includes a means for programming a value of between about 100 ms and about 200 ms and wherein the predetermined fixed period of time is in the range of about 20 ms to about 60 ms. 
   
   
       7 . A method of adjusting an operating atrio-ventricular (AV) interval in a pacing therapy delivery device, comprising:
 a) programming an operating AV interval that produces a predetermined fixed period of time between an end of a P-wave (PWend) and the beginning of one of a corresponding paced QRS complex (QRSbeg) and delivery of a ventricular pacing stimulus (Vp);   b) monitoring an atrial depolarization;   c) locating the end of a PWend associated with the atrial depolarization;   c) measuring an elapsed amount of time from the PWend to the one of the QRSbeg and the Vp;   d) comparing the predetermined fixed period of time and the measured elapsed amount of time; and
 if the predetermined fixed period of time and the measured elapsed amount of time are within about a prescribed tolerance range, storing the operating AV interval as an optimized AV (AVopt) interval in a memory of the CRT delivery device; and 
 if the predetermined fixed period of time and the measured elapsed amount of time are not within the prescribed tolerance range, modifying the operating AV interval and repeating steps a)-d). 
   
   
   
       8 . A method according to  claim 7 , further comprising:
 operating the pacing delivery device in a bi-ventricular pacing mode at the AVopt interval.   
   
   
       9 . A method according to  claim 7 , wherein the step of programming the operating AV interval comprises defining a temporal value of between of between about 80 milliseconds (ms) and 220 ms and wherein the predetermined fixed period of time is in the range of about 20 ms to about 60 ms. 
   
   
       10 . A method according to  claim 7 , wherein the modifying step further comprises:
 increasing the operating AV interval if the measured elapsed amount of time is shorter than the predetermined fixed period of time; and   decreasing the operating AV interval if the measured elapsed amount of time is longer shorter than the predetermined fixed period of time.   
   
   
       11 . A method according to  claim 7 , wherein the step of measuring the temporal cardiac parameters comprises:
 deploying one of a temporary and a chronically implanted pacing and sensing lead into communication with the heart.   
   
   
       12 . A method according to  claim 7 , wherein the step of measuring the temporal cardiac parameters comprises:
 deploying a subcutaneous cardiac sensing array into a position spaced from, but in electrical communication with, the heart.   
   
   
       13 . A method according to  claim 7 , wherein the step of measuring the temporal cardiac parameters comprises:
 deploying at least one surface sensing electrode into communication with the heart.   
   
   
       14 . A method according to  claim 7 , wherein the prescribed tolerance range comprises a temporal window of about less than 10 ms to about 20 ms. 
   
   
       15 . A method according to  claim 7 , further comprising:
 calculating a sensed-AV (SAV) interval based upon the AVopt value.   
   
   
       16 . A method according to  claim 15 , further comprising:
 monitoring heart rate (HR), and wherein the calculated SAV interval is decremented in the event that the HR is increasing.   
   
   
       17 . A method according to  claim 16 , wherein the SAV interval is decremented between about 0.25 milliseconds (ms) and about 3 ms for each additional beat per minute (bpm) the HR increases. 
   
   
       18 . A method according to  claim 7 , further comprising:
 calculating a paced-AV (PAV) interval based upon the AVopt value.   
   
   
       19 . A method according to  claim 18 , further comprising:
 monitoring heart (HR), and wherein the calculated SAV interval is decremented in the event that the HR is increasing.   
   
   
       20 . A method according to  claim 19 , wherein the SAV interval is decremented between about 0.25 milliseconds (ms) and about 3 ms for each additional beat per minute (bpm) the HR increases. 
   
   
       21 . A computer readable medium operable under computer processor control for adjusting an operating atrio-ventricular (AV) interval in a pacing therapy delivery device, comprising:
 a) instructions for programming an operating AV interval intended to produce a predetermined fixed period of time between an end of a P-wave (PWend) and the beginning of one of a corresponding paced QRS complex (QRSbeg) and delivery of a ventricular pacing stimulus (Vp);   b) instructions for monitoring an atrial depolarization;   c) instructions for locating the PWend associated with the atrial depolarization;   c) instructions for measuring an elapsed amount of time from the PWend to one of the QRSbeg and the Vp;   d) instructions for comparing the predetermined fixed period of time and the measured elapsed amount of time;   e) instructions for storing the operating AV interval as an optimized AV (AVopt) interval in a memory of the CRT delivery device if the values of the predetermined fixed period of time and the measured elapsed amount of time are within a prescribed tolerance range,   f) instructions for modifying the operating AV interval if the values of predetermined fixed period of time and the measured elapsed amount of time are not within the prescribed tolerance range; and   g) instructions for repeating the steps a) through f) until the AVopt interval is stored.   
   
   
       22 . A computer readable medium according to  claim 21 , further comprising:
 instructions for operating the pacing delivery device in a bi-ventricular pacing mode at the AVopt interval.   
   
   
       23 . A computer readable medium according to  claim 21 , wherein the instructions for programming the operating AV interval include programming a value of between about 100 milliseconds (ms) and about 200 ms. 
   
   
       24 . A computer readable medium according to  claim 21 , wherein the predetermined fixed period of time has a value of about less than 20 ms to about 60 ms.